This application is a continuation-in-part application of copending application Ser. No. 854,249 filed Apr. 21, 1986, now abandoned, and entitled IMPROVED RIM AND LOCK RING.
The present invention relates to a rim construction for mounting a tire and more particularly to rim construction for mounting tires of the type generally utilized on trucks and off-highway vehicles.
The usual rim structure for mounting large tires on equipment such as earth movers or off-road equipment includes an endless separate bead seat ring that telescopes over a rim base with one of the tire beads wedged thereon. A rim flange is retained between the tire casing and an outwardly extending flange on the bead seat ring and a projection on a lock ring, usually a split type, is inserted in a groove or gutter formed in the rim base and has a flat surface which engages a corresponding flat surface on the bead seat ring to lock these members in place on the rim base. The lock rings, such as that described in U.S. Pat. No. 3,224,484, are coiled which puts high internal stresses in the lock ring that tend to cause it to twist so that the flat surface on it does not uniformly engage the corresponding flat surface on the bead seat. Thus stresses are created in the lock ring and the members in engagement therewith which often result in failure. To overcome the twisting forces on the lock ring and try to offset them, devices are used such as a lug attached to the lock ring which extends radially in both directions beyond the ring to engage a portion of the bead seat ring and the base member to prevent the ring from twisting.
In addition, in the prior art, the rim section, including the flange, rim base and gutter, bead seat ring and lock ring are formed of hot rolled steel which, without subsequent machining, prevents a close tolerance design fit of the locking projection with the base member groove when they are assembled thus creating an unequal distribution of stress which results in failure of the metal.
The present invention overcomes the disadvantages of the prior art by providing a rim construction in which the groove or gutter in a base member is machined to a fine predetermined tolerance and the lock ring is formed by cold forming steel, without subsequent machining, in order to obtain a matching fine predetermined tolerance design fit with the gutter so that maximum contact area is formed between the gutter and the lock ring to distribute stress. Secondly, a lip extends horizontally from the lock ring and is integrally formed with the lock ring to prevent twisting of the ring. Thus stresses are evenly distributed because the lock ring projection surface has a design fit which more uniformly engages the groove or gutter surface to evenly distribute stresses therein.